Spinal surgery may include any one or more of a number of procedures. For example, a laminotomy is a surgical technique that removes a portion o the lamina (i.e. the bone at the back of the spinal canal). The small opening that is created is sometimes enough to relieve pressure from a nerve, but in some cases, part of an intervertebral disk or a bone spur that is pressing on the nerve may also be removed. Also by way of example, a laminectomy is a surgical technique that generally removes the entire lamina to relieve pressure when a disk bulges into a nerve. Further, a diskectomy is a surgical technique that removes a portion of a damaged disk from between adjacent vertebrae to relieve pressure on the nerve. Also, vertebral fusion is a surgical technique used to combine two or more vertebrae. Supplementary bone tissue (either autograft or allograft) is typically used in conjunction with the body's natural osteoblastic processes. This procedure is often used to eliminate pain caused by abnormal motion of the vertebrae by immobilizing the vertebrae themselves. Spinal fusion is done most commonly in the lumbar region of the spine, but it is also used to treat cervical and thoracic problems. There are generally two main types of lumbar spinal fusion, which may be used in conjunction with each other. Posterolateral fusion places the bone graft between the transverse processes in the back of the spine. These vertebrae are then fixed in place with screws and/or wire through the pedicles of each vertebra attaching to a metal rod on each side of the vertebrae. Interbody fusion places the bone graft between the vertebra in the area usually occupied by the intervertebral disc. The fusion then occurs between the endplates of the vertebrae.
However, such known spinal fusion techniques tend to have certain disadvantages. For example, the vertebrae that have been fused and immobilized together are no longer able to flex relative to one another to assist in the flexing the spine through a normal range of motion. Also, due to the immobility of the fused vertebrae, the spinal elements (e.g. intervertebral discs, vertebrae, etc.) that are adjacent to the fused vertebrae tend to be subject to increased flexion demands (and associated wear and tear and other related degradation) as the spine seeks to accommodate a normal range of motion. A simplified example of such a phenomenon may be seen in a flexible tube have and immobilized (i.e. rigidified) segment, whereupon bending or flexing of the entire tube tends to result in increased stress, or even damage (e.g. kinking, etc.) of the tube at the locations directly adjacent to the rigid segment. Also, other spinal surgery techniques may also tend to result in reduced capability of the remaining spinal elements to accommodate the normal range of spinal motion, or may result in undesirable (e.g. non-uniform) distribution of loading across the spinal elements. It is also generally known to provide a prosthetic spinous process, such as those described in U.S. Patent Application Publication No. US 2006/0161154 A1 titled “Prosthetic Spinous Process and Method” for use in surgical applications where the spinous process is removed or otherwise missing. However, such prosthetic spinous process devices are of limited utility or applicability in spinal surgical techniques where the spinous process remains intact following the surgery.
Accordingly, it would be desirable to provide a universal medical apparatus and method for spinal surgery that helps to overcome the disadvantages of a variety of know spinal surgical techniques and devices. It would also be desirable to provide a medical apparatus and method for spinal surgery that transfers loads (e.g. flexion loads, bending loads, etc.) and other related stresses from the locations directly adjacent to the surgery location (e.g. fused vertebrae, etc.) to other vertebrae above and/or below the surgery location by interconnecting the spinous processes of the adjacent vertebrae in a load-sharing manner, so that bending loads and other stresses may be spread over (and at least partially accommodated by) such other vertebrae to reduce wear and tear and other degradation at the locations directly adjacent to the spinal surgery location.